Time delay switch



Dec. 17, 1940. A. cLARKsoN TIME DELAY SWITCH 5 Sheets-Sheet l Filed Nov.29, 1959 Dec. 17, 1940. A. cLARKsoN 2,224,951

TIME DELAY SWITCH Filed NOV. 29, 1939 3 Sheets-Sheet 2 ...LL- I @17p/z'of Hallan/z Dec. 17, 1940.

A. cLARKsoN 2,224,951

TIME DELAY SWITCH Filed Nov. 29, 1959 3 Sheets-Sheet 3 Patented Dec. 17,1940 y 2,224,951. l f 'rma DELAY swrron Anck clarkson, BloomingdaleTownship, nu Page County, Ill., assignor to Vapor Car Heating Company,Inc., Chicago, Ill., a corporation of New York Application November 29,1939, Serial No. 306,637

8 Claims.

This invention relates to a new and improved time-delay switch forclosing either single or multiple contacts after a lapse of apredetermined time period and in which the said multiple contacts may beclosedeither simultaneously or in sequence at predetermined timeintervals.

The improved switch closes automatically in response to electricallyenergized means and is so designed that it closes with a regulated rateof movement throughout its entire travel. It is opened automatically, ata substantially faster rate, by spring pressure when the said closingmeans is de-energized and may also be opened by mechanical means, forexample, a iiuid pres, sure device, while the said electrical closingmeans remains energized. However, when the iniiuence of said mechanicalopening means is removed, while the electrically energized closing meansis effective, the switch will again move to its `closing position withthe impeded rate of movement above mentioned.

While the present switch construction may be used, as above indicated,in various situations, the improvements have special utility, because oftheir novel cooperation with the other elements, when embodied in afluid pressure control switch of the type shown in 'my copendingapplication Serial No. 242,708, filed November 28, 1938. Specificallythe present invention has been designed as an improvement on the switchstructure' shown in the said copending application and, therefore, willbe described herein as constructed and used for the same purpose, thatis to saya multiple contact starter switch for the motor of a steamgenerating plant, for example, the blower motor of a fluid-fuel burner.

The switch comprises a unitary carriage on which is supported aplurality of separate contact fingers. It is moved to its closedposition by the reiiex or contraction force of a spring which istensioned by means which are electrically energized whenever a mainswitch in a main control circuit is closed. In order to insure iheclosing of the contacts in sequence at uniform time intervals thecontraction of the switch closing spring is impeded, preferably by adash-pot device constructed to accurately control the rate of thecontracting movement of the said spring, there being provisions made forcompensating for the gradually reduced force of the spring tension asthe switch approaches its closed position. When the main control circuitis opened the starter switch will be automatically opened by means of aspring which was put under compression during vthe closing (Cl. 20o-97)movement of the switch. The said fluid-pressure means for opening theswitch to stop the motor may be set to be eiective whenever apredetermined maximum fluid-pressure isv exceeded. This member of theswitch assembly can be set to maintain any desired steam pressure Withincertain limits, for example, 150 pounds per square inch. When the motorstarter switch has been opened automatically by the rise of pressureabove the predetermined limit in the steam 10 generator, the switch,upon a sudden fall of pressure in the steam generator below thepredetermined limit, will close slowly so that the several contactfingers will be brought into circuit closing position at uniform timeintervals.

The principal object of this invention is to provide an improved timedelay switch in which the closing operation of the switch may beaccurately controlled and thereby maintain a uniform rate of movementthroughout its entire closing operation.

Another and more specific object is to provide an improved automaticallycontrolled starter switch of the type briefly described hereinabove anddisclosed more in detail in the specications which follow.

Other objects and advantages of this invention will be more apparentfrom 'the following detailed` description of one approved form of switchassembly constructed and operating according to the principles of thisinvention.

In the accompanying drawings:

Fig. l is a vertical section taken through a pressure controlled delayswitch assembly and illustrating the improved construction ofthe presentinvention.

Fig. 2 is a fragmentary view in front elevation of the upper portion ofthe assembly, showing the pressure setting and indicating mechanism.

Fig. 3 is a fragmentary sectional view similar 40 to Fig. 1 butillustrating the starter switch in its open position. Fig. 4 is a irontelevational view of the starter switch showing the relative positionsoi' the several contact lingers.

Fig. 5 is a sectional plan view taken on line 5-5 of Fig. 1, and

Fig. 6 is a wiring diagram.

The improved switch comprises a carriage or frame I0 pivotally supportedintermediate its 50 endson a fulcrum pin Il which extends through a pairof ear members I2 formed on or suitably secured to a base plate I3. Aninsulating-block Il is suitably secured to one end portion ofthe pivotedcarriage. This insulating block is prei'- 55 CFI erably formed with aplurality of grooves i5 in which are positioned the several contactngers I6, I1, I8, I9 and 20 (Fis. 4). One end of each contact finger ispivotally attached to the block by a pin 2| of insulating material. 'Iheother end of each contact nnger' is preferably yieldably supportedbetween pairs of coll springs 22 and 23 which-are seated in pocketsformed in the block I4 and in the insulating cross-bar l24 associatedtherewith. Adjustable contact: members, one for 7each contact finger,are designated I 6a, I1a, I 8a, |9a and 20a and are adapted to beaccurately positioned with relation to the iix'ed contact members,hereinafter described, with which the said adjustable contacts areengaged when the switch is movedtoits' closed position. Obviously, thesaid contacts may be so positioned as to make simultaneous contact withthe saidv cooperating fixed contact or they may ,be`po. sitioned out ofhorizontal alignment with each other, as shown inFig. 4, so that theywill move successively into engagement with the fixed contacts atsuitably spaced intervals. i' In the present disclosure the end portionsofthe contact ngers are preferably bent out of horizontal alignment, asindicated in Fig. 4, so that the operation will require less flexing ofthe contact lingers when they are positioned to move into successivecontact with the fixed contacts above vreferred to. The timing of theintervals between the closing of the contacts of the several ngers isdetermined by the spaced offset relation of the movable contactstogether with the speed of the switch closing movement.

The fixed contacts are designated 26, 21, 28, r29 and 30 (see Fig. 4).The said contacts 26 and 21 are supported on a metallic bracket 3|mounted on an insulating block 32 which in turn is suitably secured tothe base |3 ofthe switch assembly. The other fixed contacts 28, 29 and3|) are supported on a similar metallic bracket 33 which is secured tothe said insulating block 32. The purpose of the above grouping of thefixed contacts on the separate brackets 3| and 33 will appear moreclearly hereinafter from the description of the several circuits of thewiring diagram shown in Fig. 6. Each of the fixed contacts 26 to 30,inclusive, when the switch is used in a situation which requires a snapopening and closing action, is positioned between the upwardly extendinglegs of a horse-shoe shaped permanent magnet 34. It willbe apparent fromthis disclosure that when the switch carriage 6 is rocked about itspivotal axis in a switch closing direction, the contact finger I6 willbe first to move into the operating range of its permanent magnet 34,whereupon this arm will be suddenly drawn downwardly (compressing spring22) so as to engage the pair of switch contacts |6a and 26.

If the said switch isl moved at a uniform rate of speed throughout itsfull closing range the contacts |1a, |8a, |9a and 20a will be brought,

successively, into engagement with the xed contacts 21, 28, 29 and 39,respectively, at uniformly spaced time intervals, each movable contactbeing snapped downwardly by its magnet 34.

The mechanism forautomatically closing the switch comprises a solenoidcoil 35 which is housed in a casing 36 suspended from the bottom face ofthe base plate I3 (Fig. 1). The coil is centered about a vertical guidetube 31 having a core plug 38 fitted in its upper end and secured to theupper wall of the casing 36. A movable core 39 is guided within thelower portion of the guide tube 31 and through a collar is also securedto the upper end of said cylindrical extension 42, preferably by meansof a pin 45 and extends upwardll1 4through central bores 46 -ancll41formed in thef movable core 39 and the core plug l38, respectively. Theupper end of the ,push rod 44 is operatively connected with theoperating arm lila of the switch carriage. This operative connection maybe of any approved ,construction which makes adequate provisionfor/.fthe change in the angular position of the operating lever of theswitch carriage during the closing and opening movements of the switch.For the purpose oi' the present illustration, a block 48'is secured tothe upper end of the push rod 44. An upstanding web 49 on the block isformed with an open slot which receives a cross pin 49a fitted in theclevis end of the switch operating arm Ilia.

From the construction thus far described it will be apparent that whenthe starter switches are opened, as shown in Fig. 3, the movable core39, the dash pot plunger 43, and the push rod 44 will be in theirlowermost position relative to the bottom of the dash pot cylinder 56.It will also be apparent that in such position of the parts mentionedthe movable core 39 will rest on the spring 4| and the said spring willbe free of tension. By the closing ofthe Amain control switch I (seeFig.V 6), the solenoid 35 will be energized and the movable core 39 willbe drawn,

upwardly thus tensioning the spring 4| which in turn exerts resilientlifting pressure on the push rod 44 and thereby tilts the switchcarriage II) in a direction to close the several contacts thereof.,Naturally the movable core 39 will be drawn upwardly the full extent ofits travel substantially instantaneously with the closing of the maincontrol switch I. Therefore, inasmuch as the push rod 44 is liftedsolely by Athe tension force or contraction of the spring 4|, anyvariation in the voltage of the main control circuit will not ai'l'ectthe rate Aoi' the switch closing movement. relative to the core 39 islimited by a stop collar 44a which is adjustably fixed on the rod 44.

'I'he rate of the switch closing movement is controlled entirely bycontrolling the rate of contraction of the spring 4|. This result isaccomplished in the present invention by the bypassing of the uid 5|contained in the dash-pot around the dash-pot piston 43 in progressivelyincreasing volume as the piston is drawn upwardly by the tension ofthe'spring 4| The proportionate increase in the volume of fluidby-passed to a position below the dash-pot piston compensates for theproportionate reduction in the tension force of the spring 4I andthereby insures the closing of the several contacts |6a to 20a,inclusive, at uniformly spaced intervals. For the purpose ofillustrating one ap- The upward movement of the rod 44 proved means forimpeding the contraction of spring 4| so as to obtain the results abovementioned, the inner wall 52 of the dash-pot'cylinder 50 is taperedslightly so that a proportionately larger amount of the fluid 5| willpass between the dash-pot piston and the cylinder Wall, as the saidpiston is drawn upwardly. In order to provide for adjustably varying theswitch-closing time period the dash-pot piston is provided with aplurality of small leak holes 53 ot diil'ereht sizes, one or more ofwhich may be opened by adjusting the position of a disc valve 54' sothat a slot 55 in lthe valve will uncover the feed hole or holesdesired. The said disc valve is held in position `by a spring 55ainterposed between the valve and the pin I5. A ball positioned in thecylindricalextenslon 42 oi' the dash-pot piston operates to close acentral port 51 during the upward movement of the dash pot piston, butis unseated by the pressure of the iiuid I during the downward movementof said piston so as to permit free passage of uid therethrough andthereby permit a relatively fast fswitch opening movement.-

When the solenoid coil 35 is deenergized; the switch carriage I6 istilted in a clockwise direction to the switch-opening position shown inFig.

3 by means of a coil spring 58 positioned beneath the contact end of theswitch carriage so as to be compressed by the closing movement thereof.The said spring 58 is somewhat lighter than the switch-closing spring 4|and is supported on a vertically adjustable seat 56.

In addition to the spring 58 fo'r opening the switch when the controlcircuit through the solenoid 35 is broken, the switch mechanism isillustrated herein in connection with a pressure actuated device adaptedto open the switch, without disturbing the energization of .the solenoid35, when the pressure in the steam generating plant rises above apredetermined pressure. This pressure actuated means comprises an uppercasing 59, secured to and suspended from the base I3, and a lower casing68 between which a ilexlble diaphragm 6I is clamped. A pipe 62 leadingfrom the source of fluid under pressure, for example, steam, is threadedinto the nipple 63 oi the lower casing 60 and communicates throughpassage 64 with a pressure chamber 65 beneath the diaphragm 6 I. Aplunger 66 seats onthe upper face of the diaphragm 6I and extendsupwardly to a point beneath the switch carriage I 0. The upper end ofthe plunger is normally out of contact with the said switch but isadapted to press upwardly on a ball 61 secured in a suitable pocketformed `on the switch carriage body to open the switch when the steampressure in the pressure chamber 65 rises above a predeterminedpressure. The fluid pressure required to lift the plunger 66 and therebyopen the switch I0 is determined by the amount of compression impartedto spring 68, 69 which are coniined between upper and lower head members10-1l. 'I'he lower endsr of the said springs 66--69 rest on the lowerhead which `in turn is normally supported on the casing 59,

but is engaged by shoulders 16 formed on the lower end of the plunger 66when the plunger is lifted or forced upwardly by the pressure in chamber65. A movablesleeve rack 1l is movably tted on the upper end Portion ofthe switch opening plunger and seats in a self centering bearing 12formed in the upper spring head 10. Compression is imparted to the saidsprings 68-69 to correspond to a maximum selected pressure for thepressure chamber 65 by adjusting .the sleeve rack 1| vertically. Thisadjust' ment is eifected by means of a pinion 13 mounted in the casing59 to engage the teeth of the sleeve rack 1|. 'Ihe pinion shait extendsout oi the casing 59 and carries at its outer end a suitable hand wheel15 whereby the pinion 13 may be rotated to raise and lower the sleeverack 1I and thereby vary the compression of the spring 68, 69. Thepinion 13 is held in any desired adjusted position by means of clutchmechanism 16 (Fig. 2). This clutch mechanism is not illustratedspecifically in this application since its speciiic construction doesnot aect the operation of the improvements disclosed herein, it beingunderstood that any suitable form oi mechanism for locking the shaft 14against accidental rotation may be used. Preferably, a pointer 11 isoperatively secured to -the shaft 14 so as to indicate the pressure atwhich the mechanism is set to open the switch III.

Assuming now that the switch III is in its closed position, indicatedinFig. 1`, and the solenoid 35 is energized: When the iluid pressure inchamberl 66 rises above a selected maximum, for example 150 pounds persquare inch, the switch opening plunger 66 will be forcedupwardlyagainst the compression of spring 66-69 to'open the switch I8. Theopening movement of the'switch forces the switch closing plunger rod I4and dash pot plunger 43 downwardly. Inasmuch as the sole- Anoid 35remains energized the movable'core 39 remains in its upward position.Consequently the downward movement of the push rod M and dash pot 43imparts tension to the Yspring Il whereby, in .the event that thepressure in chamber 65 is suddenly lowered or reduced, the switch I0vwill ybe again closed automatically by the contraction of the spring 4land this closing movement will be retarded by the action of the dash potpiston, as previously described, to effect the uniform switch closingmovement. However, if the control circuit through the solenoid 36 shouldbe broken while the switch is held open by .the pressure operatedplunger 66, the spring 58 will supportthe switch in its opened positionwhen the plunger 66 is lowered as a result of the fall of pressure inthe chamber 65. It will be also apparent from the above description thatl1' the main control switch I should be opened and subsequently closedwhile the pressure actuated plunger 66 is in its raised position, themovable core 39 of the solenoid will move to its up position and therebyput the spring 4I under tension so that it will be effective to closethe switch I6 as-soon as the steam pressure in the chamber 65 is reducedbelow the maximum for which the pressure device is set.

The several 'conduit wires connected to the individual switch contacts,it will vbe understood, are connected with suitable terminals in a box Nshown at the left of Fig.' l.

Referring' now to Fig. 6 which illustrates a simplified wiring diagramfor the switch. At A is indicated a source of electric power forenergizing a motor B (for example, the blower motor for fluid-fuelburner) said motor having a shunt neld C. At D, E, F, G and H areindicated a plurality of similar relays. 'I'he switch contacts of relaysD to G, inclusive, are respectively opened when the relays aredeenergized. The switch contacts of the relay H are normally closed whenthe relay is deenergized, but is opened when the relay is energized.With the main control switch I open, as shown in Fig. 6. the motor B isat rest, the electro-magnet 35 is de-energized, the movable core 39 ofthe electro-magnet 35 is in its lowermost position and the switchclosing spring 4| is free of tension, and all of the starter switchesare open. Assuming now that control switch I is moved to the completelyclosed position, the movable switch contact 18 will engage the two xedcontacts 19 and 60, and movable contact 90 will engage the ilxed contact9|. The electro-magnetic device Til 35 will now be energized through thefollowing circuit: From battery A through wire 92, switch contacts 90and 9|, wire 9,9, solenoid and wire 94 back to thebattery. Theenergization of the solenoid f35` results in drawing the movable coremomentarily, 'whereupon the closing ofthe main 39 upwardly for its fulltravel, thereby tensioning the switchv closing spring 4| to impartclosing pressure to the switch I0 with lthe uniform time controlledmovementpreviously described. The

movable contact |66 'will ilrstr engage xed contact 26, thusv completing`a circuit energizing relay D as follows: frombattery Athrough wire 92,switch contacts 19 and 19, `wire 95, starter switch contacts 26 and la',wire 96, relayD and wires 91 and 98, back to the'batte'ry. The switchcontacts of rrelay D will now be closed, thus completing a circuitthrough the armaturel of the motor B as follows: from battery A throughwire 99, motor B, wire |00, resistances J, K and L, wire |0|, contactsof relay D and wires |02 Aand 98 back to the battery. At the same time ashunt circuit through the motor eld will be lcompleted as follows: fromthe wire 99, through ield C, wires |03 and |04, 4closed contacts ofrelay H and wires |05 and |06 to wire |0| and Athence as before, back tothe battery. y

Shortly thereafter the second pair of starter switch contacts |1a and 21will be engaged thus energizing'relay E through a circuit similar tothat previously described for relay D. 'Ihis will short-circuitresistance L through wire |01 and the closed contacts of relay E. In asimilar manner, vthe successive energization of relays F and Gwillsuccessively cut out the resistances K and J, thus successively buildingup the current in the motor amature circuit. When the last' pair `ofstarter switch contacts 20a and 30 are closed, the last' r'elay H willbe energized so as to open the relay switch contacts and break the shuntcircuit through wires |03 and |05 around a resistance M so that thisresistance will now be thrown into series with the held C of the motorso as to increase the motor speed. It will thus be seen that the simpleact of closing the single control switch I will cause electromagneticdevice 35, .through the resulting tension imparted to the spring Il, toeii'ect a closing of the several starter switches in properly timedrelation so as to preferably build up the current 'and speed of themotor B. If switch I is opened, magnet 35 will be de-energized, wherebythe spring 59 will then function to open all of the starter switches tostop the motor.

Assuming now that the switch I remains closed and the electro-magneticdevice 95 remains energized, if the steam or other fluid pressure in thesystem builds up above the predetermined desiredmaximumthefpressureoperated plunger 66 will function .in a manneralready described to open the starter switches and thereby stop themotor. v

It is sometimes desirable to operate the motor B for a short period atal reduced speed, for example, while warming up the system preliminary.to the normal operation. In order to do this, the switch I is moved toan intermediate position so as to engage contact 18 with xed contact 19but ^not to engage the xed contact 90. The first pair of 'relays D and Ewill now be successively energized to start the motor and then cut outresistance L, but .the motor will then be permitted to runy with theresistances K and Jin the armature circuit, and without the resistance Min the eld circuit. The closing of the remaining starter switches willbe ineifective to energize the relays F, G and H sincev the circuitsfory these 'relays are open lat the contact 90. After the system iswarmed up, the control switch I ispreferably opened to break allcircuits by theopening oi' the starter switch control switch will-thenbe effective to Vre-energize the electro-magnet 95, whereby the starterswitches will 'be closed successively at uniform time intervals in themanner first described.

I claim: l f

1. In combination with a switch,l means for automatically closing theswitch comprising `an electro-magnetically operated device in a controlclrcuit and operablefor its full movement immediately upon the closingof the control circuit and a coil spring operatively'engaging the switchand said electro-magnetically operated device, whereby the said springis stretched by the operation of said device and thereby exerts closingpressure on the switch, a dash-pot for retarding the contraction of thespring to prolong the closing movement of the switch and 2. Incombination with a switch, means for automatically closing the switchcomprising an electro-magnetically operated device in a control circuitand operable for its full movement immediately upon the closing of thecontrol circuit and a coil spring operatively engaging the switch andsaid electro-magnetically operated device, whereby the said spring isstretched by l 3. In combination with a switch, means for automaticallyclosing the switch comprising an electro-magnetically operated device ina control circuit and operable for its full movement immediately uponthe closing of the control circuit and a coil spring operativelyengaging the switch and said electro-magnetically operated device,whereby the said spring is stretched by the operation of said deviceandthereby exerts closing pressure on the switch, means for retardingthe contraction of the spring vcomprising a dash-pot having a fluidby-pass around the piston whichincreases in area in proportion to thecontraction of the spring and the consequentreduction in force lexertedthereby, whereby the switch-closing movement is maintained at a uniformrate of speed for the full travel `oi' the switch, and means foradjustably varying the retarding action of the dash-pot.

i 4. In combination, a switch comprising a plurality of fixed contactsand a plurality of cooperating movable contacts, a carriage on whichsaid movable contacts are so mounted as to engage successively with therespective fixed contacts, a spring for moving the carriage in a switchclosing direction, an electrically operated device in a control circuitand adapted upon the closing of said control circuit to make said springeffective for 'closing the switch, means for controlling the rate ofmovement of the carriage in a switch closing direction, whereby theseveral contacts are closed successively at uniformly spaced intervals,and a pressureoperated device operable at a predetermined pressure forswinging the said carriage in a switch-opening direction in oppositionto the switch-closing spring and for4 repositioning the said means forcontrolling the rate of movement of the carriage.

5. In combination, a switchcomprlsing aplurality of fixed contacts and aplurality of movable contacts, a .unitary pivoted carriage on which themovable contacts are mounted to engage successively the iixed contacts,means i'or automatically moving the said carriage in the switch-closingdirection comprising an electro-magnetically operated device in acontrol circuit and operable for its full movement immediately upon theclosing of said circuit, a coil spring operatively connecting the switchcarriage and the electro-magnetically operated device, Awhereby saidspring is tensioned by the operation of the electro-magnetic device toimpart switch-closing movement to said carriage, means for controllingthe rate of contraction of said spring, a pressure operated deviceoperable at a predetermined selected pressure for moving said carriagein a switch-opening direction while the said control circuit remainsclosed, and means for automatically moving said carriage in aswitch-opening direction when said control circuit is broken.

6. In combination, a switch comprising a plurality of fixed contacts anda plurality of movable contacts, a unitary pivoted carriage on which themovable contacts are mounted to engage successively the fixed contacts,means for automatically moving the said carriage in the switchclosingdirection comprising an electro-magnetically operated device in acontrol circuit and operable for its full movement immediately upon theclosing of said circuit, a push rod engaging the switch carriage, a coilspring operatively engaging said push rod and the electro-magneticallyoperated device, whereby said spring is tensioned by the operation, ofthe electro-magnetic device to lift the push rod and thereby impart 50switch-closing movement to said carriage, means for controlling the rateof contraction of said spring, a pressure operated device operable at apredetermined selected pressure for moving said carriage in aswitch-opening direction while the said control circuit remains closed,and means for automatically moving said carriage in a switchopeningdirection when said control circuit is broken.

7. In combination, a switch comprising a plurality of ilxed contacts anda plurality of movable contacts, a unitary pivoted carriage on which themovable contacts are mounted to engage successively the fixed contacts,means for automatically moving the said carriage in the switchclosingdirection comprising an electro-magnetically operated device in acontrol circuit and operable for its full movement immediately upon theclosing of said circuit, a push rod engaging the said switch carriage, acoil spring operatively engaging said push' rod and theelectro-magnetically operated device, whereby said spring is tensionedby the operation of the electro-magnetic device to lift the push rod andthereby impart switch-closing movement to said carriage, means forcontrolling the rate of contraction of said spring comprising a dash-pothaving a fluid bypass which increases in area. in proportion to thecontraction of the spring and including means for adjustably varying thetime period of the switch-closing operation, a pressure operated deviceoperable at a predetermined selected pressure for moving said carriagein a switch-opening direction while the said control circuit remainsclosed, and for repositioning the dash-pot piston for the control of asubsequent switch closing operation, and means for automatically movingsaid carriage in a switch-opening direction when said control circuit isbroken.

8. In combination, a switch comprising a plurality of movable contacts,a plurality of fixed contacts, a carriage on which the movable contactsare so mounted as to engage successively with the respective fixedcontacts, a spring for moving the carriage in its switch-closingdirection, an electrically operated device in a control circuit andadapted upon the closing of said control circuit to make said springeiective for closing the switch, means for controlling the rate ofmovement of the carriage in its switch closing direction, whereby theseveral contacts are closed successively at uniformly spaced intervals,

and a pressure operated device operable at a

